返す

1. Origins, structure, and basic meaning

• Structure: 返す, read かえす, is a transitive verb joining the return-related stem 返 with ending す.
• Basic usage: 本を返す means returning a borrowed object, while 借金を返す means repaying a debt.

2. Common pitfalls and similar expressions

• Distinguishing meanings
  • The returned object or repaid debt takes を, and the direction is opposite to borrowing with 借りる.